The legendary "Judo" Gene LeBell -- possibly the most badass man to ever walk the earth -- has died at the age of 89, and some of the biggest sports stars in the world are showing love in light of his passing.
LeBell passed away Tuesday ... leaving behind an incomparable legacy in mixed martial arts and wrestling.
Nicknamed the "Godfather of Grappling," LeBell's journey to stardom began when he won the heavyweight and overall Amateur Athletic Union National Judo Championships in 1954 and 1955.
LeBell is widely credited with introducing catch wrestling and grappling techniques to pro wrestling and MMA.
Speaking of MMA ... long before Royce Gracie and Ken Shamrock fought at UFC 1 (1993), Gene fought in the first televised bout in America in 1963.
Gene, with his judo and grappling, beat top-ranked light-heavyweight boxer Milo Savage.
LeBell also trained some of Hollywood's biggest names like Chuck Norris and Bruce Lee.
Gene and Bruce first met during filming of the TV show "The Green Hornet" ... and became friends, often training together.
He also served as the referee for Muhammad Ali's crossover bout with Antonio Inoki in 1976.
Gene, also an actor and stuntman, appeared in hundreds of movies (there's a totally unverified story about LeBell and Steven Seagal going at it on set -- look it up).
Expertise aside, LeBell was revered for his relationships with fighters and wrestlers over his storied career, most notably former UFC women's bantamweight champion Ronda Rousey.
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Gene trained Rousey (a former Judo star) ... and he also worked with WWE legend "Rowdy" Roddy Piper, the inspiration for the "Rowdy Ronda" character.
On Wednesday, Ronda posted a photo of her and Gene together ... captioning the pic, "Legend."
Triple H, a14-time WWE champ, took to Twitter to express his gratitude and appreciation for Gene's contributions to the industry over the years.
"Gene LeBell remained a towering figure in the history and expansion of mixed martial arts and sports entertainment," HHH wrote. "A teacher to many of the sport’s greats, his influence is felt throughout @WWE to this day."
"Our thoughts are with his family and loved ones at this time."